Exam 2 Anatomy and Physiology Dr. Perey Ohio University

Concentration gradient

region along which concentration changes and can be across a membrane (abrupt)

Electrochemical gradient

separation of ions across a membrane (usually 1+ ion)

-Difference in charge + chemicals

membrane potential

electrical charge difference across a membrane

-can be measured in millivolls (mV)

What is the membrane potential of a resting cell?

-70 to -90mV

Diffusion

Because of motion, molecules spread out to fill space (High to low conentration)

Osmosis

move from:

-High [water] to low [water]

-Low [solute] to high [solute]

Reverse osmosis

way to purify water

Tonicity

hypertonic, hypotonic, isotonic

Isotonic

same

Hypertonic

Crenate = shrink

Hypotonic

Lyse = swell

Two types of Passive transport? (require no energy)

1. Simple Diffusion

2. Facilitated Diffusion

Simple Diffusion

substances passes directly through lipid bilayer (High to low)

-osmosis

Facilitated Diffusion

Substance needs help to pass through membrane by channel or carrier proteins (High to low)

Active Transport

needs energy (ATP) and protein pumps (Low to high) against gradient

-Na+/K+ pump

Na+/K+ pump

pumps 3Na+ out and 2K+ in

-separation of ions

-separation of charge= 1+ out in extracellular fluid

Does Active transport have potential energy?

Yes. Active transport goes uphill and [] gradient contains potential energy

-energy can be stored in a gradient

-chemical energy (ATP) to gradient

Co-transport

transport of 2+ more solutes at same time

-usually couples "down gradient" transport to "against gradient"

-requires cotransporter protein

-can be symporter or antiporter

Secondary Active Transport

Energy stored in Na+ gradient from ATP and used to transport solute against gradient (ex. glucose)

Bulk Transport (vesicles)

little membrane bubbles inside cell (phospholipids) to transport stuff

-microtubules are train tracks for intracellular vesicle transport

-kinesin (motor molecules) pulling a vesicle

Exocytosis

releasing stuff to outside

-secretion (insulin)

-vesicle fuse w/ membrane

Endocytosis

Bring stuff into cell

-large molecules and particles

3 types of endocytosis

1. Pinocytosis = cell drinking (contents of vesicle are random)

2. Phagocytosis = cell eating food vacuole (pseudopodia extend around food)

3. Receptor-mediated = receptors on cell surface grab target molecules (receptors collected in vesicle and collect specific molecules)

DNA

-monomer= nucleotide

-Nitrogeneous bases= Deoxyribose

-sugar: A,T,C,G

-double stranded

-Directionality in nucleic acids= phosphate end is 5' and Free OH- end is 3'

(synthesis 5'to3' new nucleotides added to 3')

RNA

-monomer= nucelotides

-N bases= ribose

-Sugar= A,U,C,G

- 1 strand and sometimes wrap around

DNA strands are parallel or antiparallel?

Antiparallel because strands run in opposite directions and form a double helix

Chromatin

chromatin fibers (DNA + proteins)

-placed into a chromosome during cell division

chromosome

1 DNA molecule + proteins

Centromere

narrow part of chromosome near middle

Describe human chromosomes

46 per cell= 2 sets of 23

-44 autosomes = 2 sex chromsomes

-XX = female

-XY= male

Genome

all the genetic information in a cell or in an organism

genomics

study of genome (human genome project= 13 years)

Ribosome

made of proteins and RNA

-site of protein synthesis

-free in cytoplasm or bound to nuclear envelope or RER

How is polypeptide made?

DNA to RNA to protein

-Info in DNA (a gene) transferred to messenger RNA

-mRNA moves out of nucleus

-Ribosome moves along mRNA translating genetic info to amino acid sequence

-Polypeptide is threaded into ER from ribosome

Gene

unit of hereditary

-segments of DNA (genetic info + codes for an RNA product)

-mRNA, tRNA, rRNA

-1 mRNA makes 1 polypeptide

-1 gene makes 1 kind of polypeptides

Hemoglobin is made of 4 polypeptides: 2 identical alpha chains and 2 identical beta chains. How many genes are required to make hemoglobin?

3

Gene expression

Turning info into DNA into working protein

-a gene doesn't directly make a polypeptide

-is made in cytoplasm

-RNA intermediate carries info (mRNA)

Explain process of transcription

synthesis of RNA from info in DNA

-DNA strand= template strand

RNA polymerase = enzyme that reads template strand

-Pre-mRNA converted to final functional form (cap and tail splicing)

-nuclear pore allows mRNA to make polypeptide

-ribosome uses info in mRNA to make polypeptide (reads mRNA and adds appropriate AA one at a time)

genetic code

sequence of 3 bases designate AAs

Codon

triplet code

-codons read by the ribosome 5' to 3' on mRNA

-each codon specifies next AA

-redundancy

-not ambiguous: no codon codes for 2 AAs

-special codons

-stop codons

RNA processing

pre-mRNA to mRNA

-5' cap added to 5' end (modified guanine nucleotide)

-poly-A tail= an enzyme adds 50-250 A's to 3' end

Explain exons and introns

-exons = segments that code for AA

-introns = intervening sequences that do not code

-introns cut out and exons connected together

-alternatice splicing = sometimes not all exons used and cell can put different exons together in different ways

tRNA

transfer RNA (AAs to ribosome)

describe translation process

-AAs covalently link to appropriate tRNA

-tRNA match with mRNA codons on the ribosome and add AA to growing chain

-Ribosome moves alon mRNA codon by codon

Ribosome

-large and small subunit only together when bond to mRNA

-3 binding sites: A-site= entry point for tRNA bringing next AA P-site= holds tRNA connected to polypeptide E-site= exit

What are the stages of translation? (photo in notebook)

1. Initiation

2. Elongation

3. Termination

Describe the Initiation stage of translation

-Ribosomes and 1st tRNA bind to mRNA at start codon

Describe the elongation stage of translation

tRNA enters A-site and binds to codon

-growing chain transferred to A site

-New peptide bond formed

-ribosome shifts to next codon and tRNA shift position (old tRNA leaves)

Describe the termination stage of translation

Release factor = protein that binds to stop codon

Overall summary of gene expression

Inside nucleus:

Transcription

-RNA polymerase turnes DNA to mRNA

-Splicing happens (introns out just exons)

-Tail---mRNA---Cap

Outside nucleus:

Translation

-AA attachment

-Initiation, Elongation, Termination

-polypeptide

Housekeeping genes

always expressed (Constant levels) basic metabolic function, structure, etc.

-ex: cytoskeleton proteins (actin and tubulin)

Inducible genes

can be turned on and off and expression levels can be varied as needed

-Ex: iNOs (inducible nitric oxide synthase during inflammation)

Tissue specific expression

liver specific genes only turned on in lover but all genes present

-Ex: hemoglobin (only RBA) Pepsin (only chief cells in stomach)

Example of inducible gene

-hormone= prolactine

-target= mammary gland cells

-prolactine to casein gene expression (milk protein)

1. prolactine binds to receptor

2. signal is carried by signaling cascade (regulatory protein phosphorylated)

3. regulatory protein enters nucleus (binds to DNA near casein gene and turns it on)

4. transcription

5. mRNA leaves nucleus (Bound ribosome threads polypeptide into RER and is processed, collected in vesicles, sent to golgi)

6. Golgi finishing touches (secretory vesicles)

7. Exocytosis into mammary gland duct

Why do cells divide?

Growth, replacement, healing

Explain why DNA must duplicate before division

Starts with 1 set of DNA, 2 copies of DNA, 2 daughter cells with 1 copy each

DNA copying

replication

Explain process of duplicating DNA

1. Double helix unzips into template for new strands

2. nucleotides added 1 by 1 (base pairing with template and DNA polymerase)

3. Begins at origin of replication (multiple origins per chromosome in humans)

4. Replication bubble forms as DNA unzips (spread out until merge)

Cell cycle

-Sequence of events from formation of cell to its own division

-Has varying lengths (1 day, less, some not at all)

What are the three stages of cell cycle

1. Interphase

2. Mitotic phase

3. Cytokinesis

Describe interphase

-Takes up most of cell cycle

-Metabolism and growth

-3 phases:

1. G1 phase = normal cell functions

2. S phase = DNA synthesis

3. G2 phase = prep to divide

Describe mitotic division

-Division of the nucleus to equal distribution of chromosomes

-Has 4 phases:

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

Describe cytokinesis

-Division of cytoplasm

-Usually starts with anaphase/ telophase

-Cleavage furrow forms

-Contractile ring pinches cell in 2 (proteins)

-Results in 2 identical cells with some number of chromosomes

What is the G0 phase?

-The exit cell cycle at G1 some cells can re-enter

-Normal cell functions and no division

Spindle apparatus

made of microtubules and centrosomes + guides and separates chromosomes

Describe prophase

-Chromatin condense to chromosomes

-Mitotic spindle forms

-nuclear envelope disintegrates

Describe metaphase

-Chromosomes line up on plane in center of cell

Describe anaphase

-Duplicate chromosomes pulled apart by mitotic spindle towards opposite sides

Describe telophase

- Chromosomes uncoil and become chromatin

- Nuclear envelope forms

- Mitotic spindle disappears

Cell checkpoints

-wait until good to go

-Check to see if nutrients good, cell size, DNA ok?

-Growth factors for G1: signaling proteins to go

Cancer

disease of cell cycle control, uncontrolled cell division, and never cease division

-single cells get mutated

HeLa cells

Taken from Henrietta locks in 1951

-cervical cancer

-still alive today

-have been used in 1000s of experiments

What does the immune system do for cancer cells?

-Immune system often kills abnormal cells

-If cells evade the immune system then it creates a tumor

Benign tumor

Abnormal cell remain at original site and rarely deadly but can disrupt organs

Malignant tumor

Can spread through blood or lymph (metastasis) and tumors can disrupt organ function

Chemotherapy

use of cells to kill cancer cells

-many disrupt mitosis

-taxol freezes mitotic spindle

-vinblastine prevents spindle from forming

-estoposide blocks DNA replication

Histology in med takes place where

pathology lab

What are the three ways for histology in med

-Study of tissues

1. Biopsy

2. Histologist (prepare slides)

3. Pathologist (diagnose)

Microtome

super thin slides and have many different stains

Tissue

group of cells that function together to carry out specialized activities

-usually have a common origin in an embryo

Extracellular matrix (ECM)

made of proteins and polysaccharides

-is flexible, cushions, protects, resists forces, and connects cells

Collagen

most abundant protein in mammals and major component of ECM

-Strong fibers and made of 3 polypeptides (coiled coil)

what are the four types of tissues

1. Epithelial (sheet of cells)

2. Connective (few cells + lots of ECM)

3. Muscle (contractile)

4. Nervous (excitable to signals)

Epithelial tissues

Sheets of cells directly compacted and simple that have linings, coverings, protection, secretion, absorption, and filtration

Connective Tissue

Cells that have relatively few space

-Have a matrix (1 protein and ground substance)

protein fibers

collagen and elastic fibers

ground substance

stuff in between cells + fibers, often water + polysaccharides, hydroxyapatite, depends on tissue

What are three unexpected connective tissue?

Blood, bone, fat

excitability

membranes carry waves of electrical signals (membrane potential)

Neurons (nerve cells)

Receive + send electrical signals and integrrate information

Describe the structure of a neuron

- Has a cell body = soma = neurosoma (nucleus + organelles)

-several dendrites that receive signals

-axons that send signals

Neuroglia

Supporting cells that protect and nurture neurons (glia + glial cells)

What are the three types of muscle tissue

(contractile) skeletal, cardiac, smooth

Describe skeletal muscle

Muscle fibers (muscle cells/ myocytes) multinucleate, striations, voluntary

-Biceps brachii, rectus femoris, external anal sphincter

Describe smooth muscle

Involuntary, small cells, fusiform, often sheets of muscle in organ walls

-Arrector pili, walls of arteries, internal anal sphincter

Describe cardiac muscle

Cardiomyocytes, involuntary, branches, connected by intercalated discs

Cell junctions

cells connecting to other cells and ECM

Tight junctions

seals between cells and can be selectively permeable or not permeable

Adherens junctions

Holds cells together, cadherins, connect to microfilaments (adhesion belt)

Desmosomes junctions

Hold cells together, cadherins, connect to intermediate filaments